The present invention relates to a projection type video display device having a plurality of light sources. FIG. 7 is a plan view showing an optical system in a four-light and triple-plate liquid crystal projector. An illuminating device 1 comprises two light sources 1a and 1b arranged opposite to each other and two light sources 1c and 1d similarly arranged opposite to each other, an optical path changing member 2 arranged between the light sources 1a and 1b, and an optical path changing member 3 arranged between the light sources 1c and 1d. The light sources 1a and 1b are shifted upward, as shown in FIG. 8(a), with respect to the light sources 1c and 1d. Each of the light sources is composed of an extra-high pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like, and light irradiated by the light source is emitted after being changed into parallel light by a parabola reflector, and is introduced into an integrator lens 4. The integrator lens 4 comprises a pair of groups of lenses, and each lens portion introduces the light emitted from each of the light sources 1a, 1b, 1c, and 1d into the whole surface of a liquid crystal light valve, described later. A state where the light from each of the light sources is incident on the integrator lens 4 is as illustrated in FIG. 8(b). The light which has passed through the integrator lens 4 is introduced into a first dichroic mirror 7 after passing through a polarized light converter 5 and a condenser lens 6.
The first dichroic mirror 7 transmits light in a red wavelength band, while reflecting light in a cyan (green+blue) wavelength band. The light in the red wavelength band which has passed through the first dichroic mirror 7 is reflected on a reflecting mirror 9 through a concave lens 8 so that its optical path is changed. The red light which has been reflected on the reflecting mirror 9 is optically modulated by passing through a light transmission-type liquid crystal light valve for red 31 through a lens 10. On the other hand, the light in the cyan wavelength band which has been reflected on the first dichroic mirror 7 is introduced into a second dichroic mirror 12 through a concave lens 11.
The second dichroic mirror 12 transmits light in a blue wavelength band, while reflecting light in a green wavelength band. The light in the green wavelength band which has been reflected on the second dichroic mirror 12 is introduced into a light transmission-type liquid crystal light valve for green 32 through a lens 13 and is optically modulated by passing through the liquid crystal light valve 32. The light in the blue wavelength band which has passed through the second dichroic mirror 12 is introduced into a light transmission-type liquid crystal light valve for blue 33 through a relay lens 14, a total reflecting mirror 15, a relay lens 16, a total reflecting mirror 17, and a relay lens 18, and is modulated by passing through the liquid crystal light valve 33.
Modulated light beams (video light beams in respective colors) which have been modulated by passing through the liquid crystal light bulbs 31, 32, 33 are synthesized by a dichroic prism 19, to obtain color video light. The color video light is projected in enlarged fashion by a projection lens 20, and is projected and displayed on a screen 21.
Meanwhile, the first dichroic mirror 7 has the property of transmitting a wavelength larger than a certain wavelength and reflecting a wavelength shorter than the certain wavelength. However, a wavelength having a transmission rate of 50% (a half wavelength) varies depending on an angle of incidence, as shown in FIGS. 9(a) and 9(b). That is, one of an angle at which light from the light sources 1a and 1c is incident on the first dichroic mirror 7 and an angle at which light from the light sources 1b and 1d is incident on the first dichroic mirror 7 is represented by a symbol C in FIG. 9, and the other thereof is represented by a symbol B. Consequently, a difference occurs between a color component in a case where the light from the light sources 1a and 1c passes through the first dichroic mirror 7 and a color component in a case where the light from the light sources 1b and 1d passes through the first dichroic mirror 7.
Furthermore, as shown in FIGS. 10(a) and 10(b), the light transmission rate of each of the liquid crystal light bulbs 31, 32, and 33 varies depending on the angle of incidence of light. Light from a certain light source enters a certain liquid crystal light bulb leftward from the right, while entering a certain liquid crystal light valve rightward from the left. Further, light from a certain light source enters a certain liquid crystal light valve downward from the top, while entering the liquid crystal light valve 33 upward from the bottom by passing through the relay lenses 14 and 16 and the relay lens 18. The direction in which light enters a liquid crystal light valve may be reversed. That is, light entering a certain liquid crystal light valve from a certain light source is represented by a symbol C in FIG. 10, while light entering a certain liquid crystal light valve from a certain light source is represented by a symbol B.
FIGS. 11 and 12 illustrate a state where a chromaticity coordinate y in a case where only one of the light sources is put on is changed in the horizontal direction at the center of projected video, where FIG. 11(a) is a characteristic view at the time when the light source 1a is put on, FIG. 11(b) is a characteristic view at the time when the light source 1b is put on, FIG. 12(a) is a characteristic view at the time when the light source 1c is put on, and FIG. 12(b) is a characteristic view at the time when the light source 1d is put on. As apparent from the drawings, color nonuniformity and a change in white color temperature occur in putting on only one of the light sources. This is caused by a phenomenon described in FIGS. 9 and 10. On the other hand, in a state where all the four light sources 1a, 1b, 1c, and 1d are put on, the color nonuniformity is canceled by canceling the characteristics of the light sources. Accordingly, the value of Y is made constant, as shown in FIG. 13, so that the color nonuniformity is canceled, and an objective color temperature is obtained in the white color temperature.
In a state where all the four light sources 1a, 1b, 1c, and 1d are put on, as shown in FIG. 14(a) however, the color nonuniformity is canceled by canceling the characteristics, as described above. On the other hand, in a case where one of the light sources (the light source 1a in the drawing) stops emitting light by blowing its bulb, for example, as shown in FIG. 14(b) the canceling state is changed, causing color nonuniformity. From the same reason, a white color temperature is changed. It goes without saying that even in a case where two or more of the light sources stop emitting light, the canceled state may be changed, causing color nonuniformity and a change in white color temperature.
The present invention has been made in view of the above-mentioned circumstances, and has for its object to provide a projection type video display device capable of restraining, in a case where it has a plurality of light sources, the occurrence of color nonuniformity and the change in white color temperature even when one or more of the light sources stop emitting light.
In order to solve the above-mentioned problem, a projection type video display device according to the present invention is characterized by comprising an illumination optical system having a plurality of light sources for introducing light emitted from each of the light sources toward a partial area of an integrator lens to irradiate the whole area of the integrator lens; a color separation optical system for separating the light which has passed through the integrator lens into a plurality of color light beams; a light valve for modulating each of the color light beams; a projection optical system for projecting the light beam modulated by the light bulb; a detector for detecting that the light source stops emitting light; and a lights-out controller for putting out, when one of the pair of light sources having canceling characteristics with respect to color nonuniformity stops emitting light, the other light source.
According to the above-mentioned configuration, in a case where the projection type video display device has two pairs of light sources (a total of four light sources) having canceling characteristics with respect to color nonuniformity, for example, when one of the light sources stops emitting light, the detector detects that the light source stops emitting light. Accordingly, the other light source paired with the one light source is put out by the lights-out controller, so that the illuminated state is maintained in the other pair of light sources (two light sources) having canceling characteristics with respect to color nonuniformity. Therefore, the brightness is decreased, while the color nonuniformity is prevented from occurring.
A projection type video display device according to the present invention is characterized by comprising an illumination optical system having a plurality of light sources for introducing light emitted from each of the light sources toward a partial area of an integrator lens to irradiate the whole area of the integrator lens; a color separation optical system for separating the light which has passed through the integrator lens into a plurality of color light beams; a light valve for modulating each of the color light beams; a projection optical system for projecting the light beam modulated by the light bulb; a detector for detecting that the light source stops emitting light; and reporting means for urging, when one of the pair of light sources having canceling characteristics with respect to color nonuniformity stops emitting light, a user to put out the other light source.
According to the above-mentioned configuration, in a case where the projection type video display device has two pairs of light sources (a total of four light sources) having canceling characteristics with respect to color nonuniformity, for example, when one of the light sources stops emitting light, the detector detects that the light source stops emitting light, to urge the user to put out the other light source paired with the one light source. When the user puts out the other light source, therefore, the illuminated state is maintained in the other pair of light sources (two light sources) having canceling characteristics with respect to color nonuniformity. Therefore, the brightness is decreased, while the color nonuniformity is prevented from occurring.
A projection type video display device according to the present invention is characterized by comprising an illumination optical system having a plurality of light sources for introducing light emitted from each of the light sources toward a partial area of an integrator lens to irradiate the whole area of the integrator lens; a color separation optical system for separating the light which has passed through the integrator lens into a plurality of color light beams; a light valve for modulating each of the color light beams; a projection optical system for projecting the light beam modulated by the light bulb; a switch for selecting the lights-up/lights-out of the light source; and a controller for putting on/out both the pair of light sources having canceling characteristics with respect to color nonuniformity when the switch is operated.
According to the above-mentioned configuration, in a case where the projection type video display device has two pairs of light sources (a total of four light sources) having canceling characteristics with respect to color nonuniformity, for example, when the lights-out is selected by the switch, the one pair out of the two pairs of light sources is put out, thereby entering a power saved state where the brightness is decreased while preventing the color nonuniformity from occurring.
A projection type video display device according to the present invention is characterized by comprising an illumination optical system having a plurality of light sources for introducing light emitted from each of the light sources toward a partial area of an integrator lens to irradiate the whole area of the integrator lens; a color separation optical system for separating the light which has passed through the integrator lens into a plurality of color light beams; a light valve for modulating each of the color light beams; a projection optical system for projecting the light beam modulated by the light bulb; a correction data memory storing correction data previously prepared in order to cancel each of color nonuniformities which occur when any one or more of the light sources stop emitting light; a detector for detecting that the light source stops emitting light; and a video signal corrector for reading out the correction data depending on the light source which stops emitting light and correcting a video signal.
According to the above-mentioned configuration, the detector detects, when the light source stops emitting light, which of the light sources stops emitting light, the correction data previously prepared is read out as a case where the light source stops emitting light, and the video signal is corrected on the basis of the correction data. Accordingly, the color nonuniformity is restrained.
A projection type video display device according to the present invention is characterized by comprising an illumination optical system having a plurality of light sources for introducing light emitted from each of the light sources toward a partial area of an integrator lens to irradiate the whole area of the integrator lens; a color separation optical system for separating the light which has passed through the integrator lens into a plurality of color light beams; a light valve for modulating each of the color light beams; a projection optical system for projecting the light beam modulated by the light bulb; a correction data memory storing correction data previously prepared in order to cancel a change in white color temperature which occurs when any one or more of the light sources stop emitting light; a detector for detecting that the light source stops emitting light; and a video signal corrector for reading out the correction data depending on the light source which stops emitting light and correcting a video signal.
According to the above-mentioned configuration, the detector detects, when the light source stops emitting light, which of the light sources stops emitting light, the correction data previously prepared is read out as a case where the light source stops emitting light, and the video signal is corrected on the basis of the correction data. Accordingly, the change in white color temperature is restrained.
The projection type video display device may further comprise a lights-out controller for putting out any one or more of the light sources, and may be so constructed as to perform correction for canceling the color nonuniformity or correction for canceling the change in white color temperature by the video signal corrector when the light source is put out. Consequently, it is possible to reduce the number of light sources which are put on to enter an energy saving state as well as to restrain the color nonuniformity and the change in white color temperature which occur because all the light sources are not put on by the correction processing.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.